Load / Save configuration

[Reimar Bauer]

We may be should have besides Load Configuration, also Load / Save /Use functionality for the json user settings.

If the user has not setup a config he currently gets many times a hint:

INFO: Default MSS configuration in place, no user settings, see http://mss.rtfd.io/en/stable/usage.html

Instead of this hint we should start a dialog with the user, showing an initial file and hint to the documentation.

Simplest solution is to have a text box editor and a json parser trying content before it could be saved.

[Vaibhav Mehra]

@Reimar Bauer Every changes made by user should be saved as a new json file or should be overwritten on the default file provided by us?

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[Reimar Bauer]

for now only to the default one, there can be a “save as”

We have implemented that on load of a usersettings the app gets reseted to an initial state.

Currently this file is only once created and becomes shared by the hosters of the wms server component.

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[Reimar Bauer]

Added text editor for config file. Fixes #309

→ <<cset f87d78fc2388>>